As motors for vehicles gradually evolve into ones with high torque and high speed specifications, a robust design for a rotor assembly structure applied to a motor is becoming essential.
Generally, a structure of a rotor applied to an interior permanent magnet (IPM) motor is formed by forming a stacked rotor core which is formed by stacking a plurality of rotor core members in a disk shape and inserting a magnet in the rotor core.
Here, the magnet inserted in the rotor core is fixedly adhered to the magnet insertion hole using an adhesive and the like. However, in such a fixing method, when a motor is used for a long time or is used for a long time at a high temperature, since adhesive strength of the adhesive which fixes the magnet becomes weak, there are problems of the magnet moving from an original mounting position, foreign material being generated due to separation of the adhesive, and a magnet that cannot be fixed due to a glass transition phenomenon at a high temperature.
Particularly, for adhesive fixing of the magnet, a region which is not filled with the adhesive occurs in the magnet insertion hole, and such a region leads to magnetic loss.